CN112983790B - Stop control method for compressor unit and compressor unit - Google Patents
Stop control method for compressor unit and compressor unit Download PDFInfo
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- CN112983790B CN112983790B CN202110302774.XA CN202110302774A CN112983790B CN 112983790 B CN112983790 B CN 112983790B CN 202110302774 A CN202110302774 A CN 202110302774A CN 112983790 B CN112983790 B CN 112983790B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B41/00—Pumping installations or systems specially adapted for elastic fluids
- F04B41/06—Combinations of two or more pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/02—Stopping, starting, unloading or idling control
- F04B49/03—Stopping, starting, unloading or idling control by means of valves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B25/00—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby
- B63B25/02—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods
- B63B25/08—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid
- B63B25/12—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid closed
- B63B25/16—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid closed heat-insulated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H21/00—Use of propulsion power plant or units on vessels
- B63H21/38—Apparatus or methods specially adapted for use on marine vessels, for handling power plant or unit liquids, e.g. lubricants, coolants, fuels or the like
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
- F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
- F04B37/18—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use for specific elastic fluids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
- F04B39/10—Adaptations or arrangements of distribution members
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/02—Stopping, starting, unloading or idling control
- F04B49/03—Stopping, starting, unloading or idling control by means of valves
- F04B49/035—Bypassing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/22—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by means of valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
- F17C2227/01—Propulsion of the fluid
- F17C2227/0128—Propulsion of the fluid with pumps or compressors
- F17C2227/0171—Arrangement
- F17C2227/0185—Arrangement comprising several pumps or compressors
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Ocean & Marine Engineering (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Abstract
The invention discloses a stop control method of a compressor unit and the compressor unit. The stop control method includes: a closing step of closing the on-off valve in response to a stop signal for stopping the non-oil-feed type first compression unit and the oil-feed type second compression unit; a first discharge step of discharging the target gas on the downstream side of the on-off valve; and a second discharge step of opening the on-off valve and a discharge valve provided in a discharge flow path branched from the demand side supply flow path after the pressure of the target gas between the on-off valve and the second compression unit is lower than the pressure of the target gas between the first compression unit and the on-off valve, and discharging the target gas on the upstream side of the on-off valve through the discharge flow path. Accordingly, when the compressor unit is stopped, the lubricating oil is prevented from flowing into the first compression part driven in the oil-less mode.
Description
Technical Field
The present invention relates to a compressor unit that supplies a target gas, which is a boil-off gas, from an LNG storage tank of a ship to a demand side, and a control method for stopping the compressor unit.
Background
A compressor unit has been developed which boosts a boil-off Gas generated from LNG (Liquefied Natural Gas) and supplies the boosted boil-off Gas to a demand side such as an engine (see japanese patent application laid-open No. 6371930). The compressor unit disclosed in japanese patent application laid-open No. 6371930 has 5 compression stages arranged to sequentially increase the pressure of the boil-off gas. Of these, the upstream-side 3 compression stages are configured to be driven without supply of lubricating oil (i.e., no-feed type), and the remaining 2 compression stages are configured to be driven with supply of lubricating oil (i.e., feed type).
When the compressor unit is stopped, if it is desired to discharge the high-pressure boil-off gas remaining in the compressor unit (so-called decompression), the lubricating oil used in the compression stage on the downstream side slightly flows backward and may flow into the compression stage on the upstream side driven in the oil-starved manner. In order to prevent the backflow of the lubricating oil, a method of disposing a check valve between the upstream compression stage and the downstream compression stage may be considered.
Disclosure of Invention
The invention aims to provide a stop control method of a compressor unit and the compressor unit, which can prevent lubricating oil from flowing into a compressor part driven in an oil-feeding-free mode when the compressor unit stops.
The stop control method according to one aspect of the present invention is applicable to a compressor unit that is installed in a ship, compresses a target gas, which is an boil-off gas, sucked from a liquefied natural gas storage tank of the ship, and supplies the compressed target gas to a demand side through a demand side supply flow path. The compressor unit includes: an intermediate check valve provided in a flow path connecting the first compression unit of the no-oil-feed type and the second compression unit of the oil-feed type; and an on-off valve disposed between the first compression unit and the intermediate check valve, wherein the second compression unit further compresses the target gas compressed by the first compression unit. The stop control method includes the steps of: a closing step of closing the on-off valve in response to a stop signal for stopping the compressor unit; a first discharge step of discharging the target gas on a downstream side of the on-off valve by opening a discharge valve provided in a discharge flow path that branches from the demand-side supply flow path; and a second discharge step of opening the on-off valve after the pressure of the target gas between the on-off valve and the second compression unit is lower than the pressure of the target gas between the first compression unit and the on-off valve, and discharging the target gas on the upstream side of the on-off valve through the discharge flow path.
A compressor unit according to another aspect of the present invention is used in the stop control method. The compressor unit includes: a first compression part of oil-free type; an oil-feed type second compression unit for further compressing the gas to be compressed in the first compression unit; an on-off valve provided in a flow path connecting the first compression unit and the second compression unit; a control unit that closes the on-off valve in accordance with a stop signal for stopping the first compression unit and the second compression unit; a first pressure detecting unit that detects a pressure of the target gas between the first compressing unit and the on-off valve; a second pressure detecting unit that detects a pressure of the target gas between the on-off valve and the second compressing unit; and an intermediate check valve provided in a flow path from the opening/closing valve to the second compression section. The control unit opens the on-off valve when the pressure detected by the second pressure detection unit is lower than the pressure detected by the first pressure detection unit.
According to the present invention, when the compressor unit is stopped, the lubricating oil can be prevented from flowing into the compression unit driven in the no-oil-feed type.
The objects, features and advantages of the present invention will become more apparent from the detailed description and accompanying drawings.
Drawings
Fig. 1 is a schematic diagram of a compressor unit according to an embodiment of the present invention.
Fig. 2 is a schematic flowchart of the decompression control performed when the compressor unit is stopped.
Detailed Description
Fig. 1 is a schematic view of a compressor train 100. A compressor package 100 is described with reference to fig. 1.
The compressor train 100 is installed in a ship (not shown) having an LNG storage tank 101 for storing LNG (Liquefied Natural Gas). The compressor unit 100 sucks a target gas (boil off gas) generated in the LNG storage tank 101 and compresses the sucked target gas. Specifically, the compressor unit 100 boosts the target gas to about 300barG (30 MPaG), and supplies the boosted target gas to the specified demand source 600. In the following description, terms "upstream" and "downstream" are used with reference to the flow direction of the target gas.
The compressor unit 100 includes: a flow path 110 through which the target gas flows toward the demand side 600; a reliquefaction line 440 branching from the flow path 110; first to sixth compression stages 201 to 206 for sequentially boosting the pressure of the object gas; and a plurality of coolers 281 to 285. The compressor unit 100 further includes a drive unit (not shown) for driving the first to sixth compression stages 201 to 206. The drive unit includes a drive source (a motor, an engine, and the like) and a crank mechanism that transmits power of the drive source to the first compression stage 201 to the sixth compression stage 206. In the compressor unit 100, the first to sixth compression stages 201 to 206 and the driving unit are integrally formed.
The first compression stage 201 to the sixth compression stage 206 are each of a reciprocating type. The flow path 110 is provided with 2 first compression stages 201, and the flow path 110 is provided with 1 second compression stage 202 to sixth compression stage 206. The first compression stage 201 to the sixth compression stage 206 each include: a cylinder portion; a piston accommodated in the cylinder portion; a piston ring mounted on the piston; a piston rod extends from the piston and is connected to the crank mechanism.
The first to fifth compression stages 201 to 205 are oil-starved compression stages that do not supply lubricating oil to the piston rings and the rod seal rings. On the other hand, the sixth compression stage 206 is an oil-feeding type compression stage for supplying lubricating oil to the piston rings and the rod seal ring. In the following description, when the compression stages of the oil-less type and the oil-feeding type are distinguished, the first to fifth compression stages 201 to 205 are generically referred to as "first compression portion 291" of the oil-less type, and the sixth compression stage 206 is referred to as "second compression portion 292" of the oil-feeding type.
The crankshaft mechanism has a plurality of crosshead connected to the piston rods of the first compression stage 201 to the sixth compression stage 206, respectively. The crank mechanism converts rotation of the crankshaft into reciprocating motion of the crosshead, thereby reciprocating the piston rod and the piston connected to the distal end of the piston rod.
The flow path 110 connects the LNG storage tank 101 and the demand side 600 so that the boil-off gas generated in the LNG storage tank 101 can be supplied to the demand side 600. The flow path 110 includes a storage tank connection flow path 111, a plurality of stage connection flow paths 115 to 119, and a request side supply flow path 114.
The storage tank connection line 111 has an upstream end connected to the LNG storage tank 101 and a downstream end connected to the first compression stage 201 of the compressor train 100. Specifically, the storage tank connection passage 111 includes a main pipe 121 extending from an upper portion of the LNG storage tank 101, and branch pipes 122 and 123 branching into two branches at a downstream end of the main pipe 121 and connected to the 2 first compression stages 201. That is, 2 first compression stages 201 are connected to 2 branch pipes 122 and 123 in parallel with each other.
The stage connecting channels 115-119 are arranged so that the target gas flows from 1 compression stage to the next compression stage. The stage connection flow path 115 flows the target gas from the 2 first compression stages 201 to the second compression stage 202. That is, the stage connecting passage 115 includes a main pipe 124 extending from the second compression stage 202 toward the first compression stage 201, and branch pipes 125 and 126 branching into two at an upstream end of the main pipe 124 and connected to 2 first compression stages 201. The stage connecting flow path 116 connects the second compression stage 202 and the third compression stage 203. The stage connecting passage 117 connects the third compression stage 203 and the fourth compression stage 204. The stage connection flow path 118 connects the fourth compression stage 204 and the fifth compression stage 205. The stage connecting flow path 119 connects the fifth compression stage 205 and the sixth compression stage 206. That is, the stage connection flow path 119 is a flow path connecting the first compression part 291 of the no-oil-feed type and the second compression part 292 of the oil-feed type.
The consumer supply flow path 114 is a flow path connecting the sixth compression stage 206 to the consumer 600.
The reliquefaction line 440 branches from the stage connection flow path 119 on the upstream side of the opening/closing valve 425 described later. The reliquefaction line 440 is connected to the LNG storage tank 101. A device (e.g., a heat exchanger) for liquefying the target gas discharged from the fifth compression stage 205 is disposed in the reliquefaction line 440.
The coolers 281 to 285 exchange heat between the target gas and cooling water having a lower temperature than the target gas. The cooler 281 is provided in the stage connecting flow path 116 so as to cool the target gas discharged from the second compression stage 202. The cooler 282 is provided in the stage connecting passage 117 so as to cool the target gas discharged from the third compression stage 203. The cooler 283 is provided in the stage connecting passage 118 so as to cool the target gas discharged from the fourth compression stage 204. The cooler 284 is provided in the stage connecting flow path 119 so as to cool the target gas discharged from the fifth compression stage 205. The cooler 285 is provided in the demand side supply passage 114 so as to cool the target gas discharged from the sixth compression stage 206.
The compressor unit 100 includes 4 bypass passages 411 to 414, 5 pressure sensors 431 to 435, an opening/closing valve 425, a discharge valve 426, a check valve 427, a discharge passage 415, an intermediate check valve 428, and a control unit 420. The bypass passages 411 to 413 are provided to return the target gas discharged from the second compression stage 202, the third compression stage 203, and the fifth compression stage 205 of the oil-starved first compression part 291 to the upstream side. Hereinafter, the bypass passages 411 to 413 will be referred to as "first bypass passages 411 to 413". The bypass passage 414 is provided corresponding to the oil feed type second compression portion 292. Hereinafter, the bypass passage 414 is referred to as a "second bypass passage 414".
The first bypass flow path 411 bypasses the first compression section 201 and the second compression section 202. The first bypass flow path 412 bypasses the third compression section 203. The first bypass flow path 413 bypasses the fourth compression stage 204 and the fifth compression stage 205.
The second bypass flow path 414 bypasses the sixth compression stage 206. The connection portion 417 of the second bypass passage 414 to the block connection passage 119 is located downstream of the connection portion 416 of the first bypass passage 413 to the block connection passage 119.
The first bypass valves 421 to 423 are respectively installed in the first bypass passages 411 to 413. The first bypass valves 421 to 423 are electrically connected to the control unit 420, and the opening degree can be adjusted under the control of the control unit 420. The second bypass valve 424 is installed in the second bypass flow path 414. The second bypass valve 424 is also electrically connected to the control unit 420, and the opening degree can be adjusted under the control of the control unit 420.
The pressure sensor 431 is attached to the segment connecting flow path 116. The pressure sensor 432 is attached to the segment connecting passage 117. The pressure sensor 433 (first pressure detecting unit) is installed between the fifth compression stage 205 and the opening/closing valve 425 in the stage connection flow path 119. The pressure sensor 435 (second pressure detecting unit) is installed between the sixth compression stage 206 and the opening/closing valve 425 in the stage connection passage 119. The pressure sensor 434 is installed in the demand side supply flow path 114.
The pressure sensors 431-435 output signals representing detected pressure values. Signals output from the pressure sensors 431 to 435 are input to the control unit 420.
An intermediate check valve 428 is mounted on the segment connecting flow path 119. By providing the intermediate check valve 428 in the stage connection flow path 119, the target gas is prevented from flowing backward from the second compression part 292 to the first compression part 291, and the target gas is allowed to flow from the first compression part 291 to the second compression part 292.
The opening/closing valve 425 is attached to the stage connection flow path 119 on the upstream side of the intermediate check valve 428. Further, a connection portion 416 of the first bypass passage 413 to the stage connection passage 119 is located upstream of the on-off valve 425 and the intermediate check valve 428. The connection portion 417 of the second bypass passage 414 to the segment connection passage 119 is located downstream of the opening/closing valve 425 and the intermediate check valve 428.
The discharge flow path 415 branches from the demand side supply flow path 114 on the downstream side of the connection portion 418 of the second bypass flow path 414, and is connected to the combustion apparatus 500. The discharge valve 426 is attached to the discharge flow path 415. The discharge valve 426 and the on-off valve 425 are electrically connected to the controller 420 to be opened or closed under the control of the controller 420.
The check valve 427 is disposed on the downstream side of the connection portion 419 in the demand side supply flow path 114. The check valve 427 is provided in the demand side supply flow path 114, thereby preventing the upstream reverse flow of the target gas from the demand side 600 and allowing the target gas to flow to the demand side 600. The check valve 427 prevents a reverse flow from the demand source 600 when the compressor unit 100 is stopped (including when the decompression process is performed).
The control unit 420 adjusts the opening degrees of the first bypass valves 421 to 423 and the second bypass valve 424 based on the pressure detection values of the pressure sensors 431 to 434 when the compressor unit 100 is driven.
Next, the operation of the compressor unit 100 will be described. When the compressor unit 100 is driven, the opening/closing valve 425 is opened and the discharge valve 426 is closed. In this state, the first to sixth compression stages 201 to 206 are driven. The target gas is compressed in sequence by the first to sixth compression stages 201 to 206. The target gas discharged from the second to sixth compression stages 202 to 206 is cooled by passing through coolers 281 to 285. After the compression processing in the first to sixth compression stages 201 to 206 and the cooling processing in the coolers 281 to 285, the target gas is supplied to the demand side 600 through the demand side supply passage 114.
Here, the pressure of the target gas in the flow path 110 is acquired by the pressure sensors 431 to 434. When the pressure detection values of the pressure sensors 431 to 434 are within a predetermined normal range set in advance, the first bypass valves 421 to 423 and the second bypass valve 424 are closed.
In the case where the pressure detection value of the pressure sensor 431 exceeds the normal range, the first bypass valve 421 is opened, and the target gas is returned from the downstream side of the second compression stage 202 to the upstream side of the first compression stage 201. Accordingly, the pressure on the discharge side (i.e., the downstream side) of the second compression stage 202 decreases. Similarly, in the case where the pressure detection value of the pressure sensor 432 exceeds the normal range, the first bypass valve 422 is opened, and the target gas is returned from the downstream side to the upstream side of the third compression stage 203.
In the case where the pressure detection value of the pressure sensor 433 exceeds the normal range, the first bypass valve 423 is opened, and the target gas is returned from the downstream side of the fifth compression stage 205 to the upstream side of the fourth compression stage 204. Instead of the pressure sensor 433, the opening degree of the first bypass valve 423 may be controlled based on the pressure sensor 435.
When the pressure detection value of the pressure sensor 434 exceeds the normal range, the second bypass valve 424 is opened, and the target gas is returned to the upstream side of the sixth compression stage 206 and the downstream side of the opening/closing valve 425.
In the compressor unit 100, if a stop signal is output from a device requiring a stop, the control unit 420 stops the driving source of the crank mechanism to stop the first to sixth compression stages 201 to 206. At this time, a pressure reduction control for reducing the pressure of the target gas in the flow path 110 is performed. Fig. 2 is a flowchart schematically showing the pressure reduction control.
If the control portion 420 receives a signal instructing the pressure reduction control (step S110), a closing step of closing the opening and closing valve 425 is performed (step S120). When the opening/closing valve 425 is closed, the movement of the target gas between the first compression part 291 (i.e., the first to fifth compression stages 201 to 205) and the second compression part 292 (i.e., the sixth compression stage 206) is restricted. In addition, the first bypass valves 421 to 423 are opened, and the first to fifth compression stages 201 to 205 are equalized. On the other hand, the second bypass valve 424 is closed. Accordingly, the oil is prevented from returning to the suction side of the second compression unit 292 through the second bypass passage 414.
After the closing step, the controller 420 opens the discharge valve 426 to execute the first discharge step (step S130). The target gas on the downstream side of the on-off valve 425 passes through the sixth compression stage 206, the demand side supply passage 114, and the discharge passage 415 in this order and is directed toward the combustion apparatus 500. As a result, the pressure of the target gas on the downstream side of the opening/closing valve 425 decreases. Since the on-off valve 425 is closed, the pressure of the target gas on the upstream side of the on-off valve 425 does not change.
The control unit 420 compares the pressure detection value of the pressure sensor 433, which is the first pressure detection unit that detects the pressure on the discharge side of the fifth compression stage 205, with the pressure detection value of the pressure sensor 435, which is the second pressure detection unit that detects the pressure on the suction side of the sixth compression stage 206 (step S140). If it is confirmed that the pressure on the suction side of the sixth compression stage 206 (i.e., the pressure on the downstream side of the opening/closing valve 425) is the same as or less than the pressure on the discharge side of the fifth compression stage 205 (i.e., the pressure on the upstream side of the opening/closing valve 425), the first discharge step ends (step S140: yes). Accordingly, the decompression of the second compression part 292 is completed.
Next, the control unit 420 opens the on-off valve 425 and executes the second discharge step (step S150). The target gas on the upstream side of the on-off valve 425 passes through the sixth compression stage 206, the demand side supply passage 114, and the discharge passage 415 in this order and is directed toward the combustion apparatus 500. Accordingly, the decompression of the first compression portion 291 is also completed. In this case, the second bypass passage 414 may be opened to allow the target gas to pass through the second bypass passage 414.
As described above, in the embodiment according to the present invention, the second compression part 292 is first decompressed and then the first compression part 291 is decompressed in a state where the opening/closing valve 425 is closed. Accordingly, the lubricating oil present in the second compression part 292 and its surroundings is prevented from flowing back to the first compression part 291 when the first compression part 291 is depressurized. As a result, the lubricating oil is also inhibited from flowing into the reliquefaction line 440.
In the second discharge step, since the first bypass valves 421 to 423 are opened, the high-pressure gas in the first to fifth compression stages 201 to 205 can be discharged in a short time.
In the compressor unit 100, an intermediate check valve 428 is attached to the stage connecting passage 119 connecting the first compression part 291 and the second compression part 292 in addition to the opening/closing valve 425. Accordingly, the backflow of the target gas from the second compression unit 292 to the first compression unit 291 is more reliably prevented, and the reliability of the compressor unit 100 can be improved.
Since the intermediate check valve 428 is provided on the downstream side of the on-off valve 425, the lubricating oil is suppressed from adhering to the on-off valve 425. This further reduces the possibility of the lubricating oil mixing into the first compression part 291.
The embodiments disclosed herein are illustrative in all respects and should not be construed as being limiting. The scope of the present invention is defined by the claims rather than the description above, and includes all modifications equivalent in meaning and scope to the claims.
In the embodiment, the first compression part 291 is composed of the first compression stage 201 to the fifth compression stage 205. Alternatively, the first compression portion 291 may be formed of less than 5 compression stages, or may be formed of more than 5 compression stages. The second compression part 292 is constituted by 1 compression stage (sixth compression stage 206). Alternatively, the second compression part 292 may be formed of a plurality of compression stages.
In the illustrated embodiment, the compressor train 100 has 2 first compression stages 201. Alternatively, the compressor train 100 may also have 1 first compression stage 201. The compressor train 100 of the above-described embodiment has a structure in which the plurality of compression stages 201 to 206 are driven by a common drive unit, but a structure in which the first compression part 291 (compression stages 201 to 205) and the second compression part 292 (compression stage 206) are driven by separate drive units may be adopted.
The compressor unit described in connection with the above-described embodiments mainly has the following features.
The stop method according to one aspect of the above embodiment is applicable to a compressor unit that is installed in a ship, compresses a target gas, which is an boil-off gas, sucked from a liquefied natural gas storage tank of the ship, and supplies the compressed target gas to a demand side through a demand side supply flow path. The compressor unit includes: an intermediate check valve provided in a flow path connecting the first compression unit of the no-oil-feed type and the second compression unit of the oil-feed type; and an on-off valve disposed between the first compression unit and the intermediate check valve, wherein the second compression unit further compresses the target gas compressed by the first compression unit. The stop control method includes the steps of: a closing step of closing the on-off valve in response to a stop signal for stopping the compressor unit; a first discharge step of discharging the target gas on a downstream side of the on-off valve by opening a discharge valve provided in a discharge flow path that branches from the demand-side supply flow path; and a second discharge step of opening the on-off valve after the pressure of the target gas between the on-off valve and the second compression unit is lower than the pressure of the target gas between the first compression unit and the on-off valve, and discharging the target gas on the upstream side of the on-off valve through the discharge flow path.
According to the above configuration, when the compressor unit is stopped, the on-off valve between the first compression unit and the second compression unit is closed (closing step), and therefore the target gas is prevented from flowing backward to the first compression unit. In this state, the target gas on the downstream side of the opening and closing valve is discharged (first discharge step). After the pressure of the target gas between the on-off valve and the second compression part is lower than the pressure of the target gas between the first compression part and the on-off valve, the on-off valve is opened (second discharge step). Accordingly, the target gas on the upstream side of the opening/closing valve is discharged through the discharge passage. Through the above steps, the compressor unit can be decompressed while preventing oil from flowing from the second compression unit into the first compression unit. Further, since the intermediate check valve is provided, the oil is more reliably prevented from flowing into the first compression portion.
In the above configuration, the demand-side supply flow path may be provided with a check valve at a position downstream of the discharge flow path.
According to the above configuration, during stop control of the compressor unit, the target gas can be discharged while preventing the target gas from flowing backward from the demand side.
In the above configuration, the compressor unit may include: a second bypass passage for returning the target gas discharged from the second compression section to an upstream side of the second compression section and a downstream side of the on-off valve; and a second bypass valve provided in the second bypass flow path. The second bypass valve may also be closed during the first exhaust step.
According to the above configuration, since the second bypass valve is closed in the first discharge step, the oil is prevented from returning to the suction side of the second compression unit through the second bypass passage.
In the above configuration, the first compression unit may include a plurality of compression stages for sequentially compressing the target gas. The compressor train may also include: a first bypass flow path which returns the target gas discharged from the plurality of compression stages to 1 or 2 or more upstream sides; and a first bypass valve provided in the first bypass flow path. In the second discharge step, the first bypass valve may also be opened.
According to the above configuration, since the first bypass valve is opened, the target gas in the first compression part can be discharged quickly.
A compressor unit according to another aspect of the above embodiment is used in the stop control method. The compressor unit includes: a first compression part of oil-free type; an oil-feed type second compression unit for further compressing the gas to be compressed in the first compression unit; an on-off valve provided in a flow path connecting the first compression unit and the second compression unit; a control unit that closes the on-off valve in accordance with a stop signal for stopping the first compression unit and the second compression unit; a first pressure detecting unit that detects a pressure of the target gas between the first compressing unit and the on-off valve; a second pressure detecting unit that detects a pressure of the target gas between the on-off valve and the second compressing unit; and an intermediate check valve provided in a flow path from the opening/closing valve to the second compression unit. The control unit opens the on-off valve when the pressure detected by the second pressure detection unit is lower than the pressure detected by the first pressure detection unit.
Industrial applicability
The technique according to the above-described embodiment is suitably used for a compressor unit mounted on a ship.
Claims (5)
1. A stop control method for a compressor unit provided in a ship, compressing target gas, which is boil-off gas sucked from a liquefied natural gas storage tank of the ship, and supplying the compressed target gas to a demand side through a demand side supply flow path,
the compressor unit includes: an intermediate check valve provided in a flow path connecting the first compression unit of the no-oil-feed type and the second compression unit of the oil-feed type; an on-off valve disposed between the first compression portion and the intermediate check valve; a discharge flow path branched from the demand side supply flow path; and a discharge valve provided in the discharge flow path, wherein the second compression unit further compresses the target gas compressed by the first compression unit,
the stop control method includes the steps of:
a closing step of closing the on-off valve in response to a stop signal for stopping the compressor unit;
a first discharge step of opening the discharge valve to discharge the target gas on a downstream side of the on-off valve from the discharge flow path; and
and a second discharge step of opening the on-off valve after the pressure of the target gas between the on-off valve and the second compression unit is lower than the pressure of the target gas between the first compression unit and the on-off valve, and discharging the target gas upstream of the on-off valve through the discharge flow path.
2. The stop control method of a compressor unit according to claim 1,
the demand-side supply flow path is provided with a check valve at a position downstream of the discharge flow path.
3. The stop control method of a compressor unit according to claim 1 or 2,
the compressor unit includes: a second bypass passage for returning the target gas discharged from the second compression section to an upstream side of the second compression section and a downstream side of the on-off valve; and a second bypass valve provided in the second bypass flow path,
in the first purge step, the second bypass valve is closed.
4. The stop control method of a compressor unit according to claim 1 or 2,
the first compression unit includes a plurality of compression stages for sequentially compressing a target gas,
the compressor unit includes: a first bypass flow path which returns the target gas discharged from the plurality of compression stages to 1 or 2 or more upstream sides; and a first bypass valve provided in the first bypass flow path,
in the second discharge step, the first bypass valve is opened.
5. A compressor unit for use in the stop control method according to any one of claims 1 to 4, the compressor unit comprising:
a first compression part of oil-free type;
an oil-feed type second compression unit for further compressing the gas to be compressed in the first compression unit;
an on-off valve provided in a flow path connecting the first compression unit and the second compression unit;
a control unit that closes the on-off valve in accordance with a stop signal for stopping the first compression unit and the second compression unit;
a first pressure detecting unit that detects a pressure of the target gas between the first compressing unit and the on-off valve;
a second pressure detecting unit that detects a pressure of the target gas between the on-off valve and the second compressing unit; and
an intermediate check valve provided on a flow path from the opening-closing valve toward the second compression portion, wherein,
the control unit opens the on-off valve when the pressure detected by the second pressure detection unit is lower than the pressure detected by the first pressure detection unit.
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| JP2020-111391 | 2020-06-29 | ||
| JP2020111391A JP6756065B1 (en) | 2020-06-29 | 2020-06-29 | Compressor unit stop control method and compressor unit |
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| JP7022245B1 (en) * | 2021-08-05 | 2022-02-17 | 株式会社神戸製鋼所 | Compressor unit and control method of compressor unit |
| JP7009669B1 (en) * | 2021-08-31 | 2022-01-25 | 株式会社神戸製鋼所 | How to operate the compressor unit, screw compressor and compressor unit |
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| WO2009112479A1 (en) * | 2008-03-10 | 2009-09-17 | Burckhardt Compression Ag | Device and method for preparing liquefied natural gas (lng) fuel |
| JP5568518B2 (en) * | 2011-06-22 | 2014-08-06 | 株式会社神戸製鋼所 | Steam-driven compressor |
| KR101386543B1 (en) * | 2012-10-24 | 2014-04-18 | 대우조선해양 주식회사 | System for treating boil-off gas for a ship |
| JP6524485B2 (en) * | 2015-04-24 | 2019-06-05 | 株式会社三井Ｅ＆Ｓマシナリー | Boil off gas utilization system |
| JP2017131862A (en) * | 2016-01-29 | 2017-08-03 | 株式会社神戸製鋼所 | Gas supply apparatus and method for stopping operation of gas supply apparatus |
| KR102066635B1 (en) * | 2018-06-08 | 2020-01-15 | 대우조선해양 주식회사 | BOG Reliquefaction System for Vessels and Method of Discharging Lubrication Oil in the Same |
| JP6605776B1 (en) * | 2019-04-09 | 2019-11-13 | 株式会社神戸製鋼所 | Compressor unit and method for stopping compressor unit |
| JP6595143B1 (en) * | 2019-07-03 | 2019-10-23 | 株式会社神戸製鋼所 | Compressor unit and control method of compressor unit |
| JP6625783B1 (en) * | 2019-08-23 | 2019-12-25 | 株式会社神戸製鋼所 | Compressor unit |
| KR102239827B1 (en) * | 2019-10-11 | 2021-04-14 | 대우조선해양 주식회사 | Fuel gas supply system and method for a ship |
| KR102276354B1 (en) * | 2019-11-20 | 2021-07-13 | 대우조선해양 주식회사 | Boil-Off Gas Re-liquefaction System for Vessels and Method for Operation of the Same |
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| JP6756065B1 (en) | 2020-09-16 |
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